In related art of FIGS. 5-8, a touch display apparatus 10 is shown to include a touch display panel 11 and a backlight module 12 below the touch display panel 11. The backlight module 12 provides light to the touch display panel 11. The touch display panel 11 includes a first polarizer 111, a substrate 112, a color filter layer 113, a liquid crystal layer 114, a thin film transistor (TFT) array substrate 115, and a second polarizer 116, which are sequentially arranged. The color filter layer 113 includes a plurality of color filters 1131 spaced from each other and a plurality of black spacers 1132. Each black spacer 1132 is disposed between two adjacent color filters 1131. The touch display panel 11 further includes a touch electrode layer 117 having touch electrodes 1170 (as shown in FIG. 6) arranged in a matrix. Each touch electrode 1170 includes sub-electrodes 1171, for example in a pattern. Only the sub-electrodes 1171 in one touch electrode 1170 are shown in FIG. 5. A space 1172 is formed between two adjacent sub-electrodes 1171. Each sub-electrode 1171 faces one of the color filters 1131. A width of one of the sub-electrodes 1171 along a specified direction parallel with the surface of the color filter layer 113 equals a width of the corresponding color filter 1131 along the specified direction. The backlight module 12 includes a light source 121 and a brightness enhancement film (BEF) 122. The BEF 122 concentrates light emitted by the light source 121 toward the touch display panel 11 for improving the brightness of the touch display panel 11. The BEF 122 includes a plurality of auxiliary structures 1221 spaced from each other. The auxiliary structures 1221 protrude from a surface of the BEF 122 facing the touch display panel 11. A cross-section of the auxiliary structures 1221 is substantially triangular. A maximum width of each of the auxiliary structures 1221 along the specified direction equals a width of one of the color filters 1131 along the specified direction. When viewed along a direction perpendicular to the touch display apparatus 10, projections of the color filters 1131 and the auxiliary structures 1221 fill the spaces 1172 and, with the sub-electrodes 1171, form visible dark lines because of refraction of light. A moiré phenomenon is thus created. FIG. 7 and FIG. 8 show this phenomenon. A better structure of the touch display apparatus is needed for preventing the moiré pattern and acquiring a better display effect.